This invention relates to the production of capsules containing a fabric antistat/softener material and a process for so producing. The present invention additionally relates to a liquid fabric conditioning composition containing the capsules.
In the conventional home laundering process, soiled fabrics are subjected to cleaning with a detergent composition in the main wash cycle and rinsing with water in the final cycle. Optionally, during the rinsing cycle a fabric conditioning composition is added. Such compositions contain a fabric softener or fabric antistat material for imparting to the rinsed fabrics' softening and antistat properties. The rinsed fabrics are oftentimes, thereafter, dried in an automatic clothes dryer.
A long-standing problem has been how to deliver the fabric conditioning agents during the rinse cycle and have the benefits retained after the drying operation. It is difficult to deliver the fabric conditioning agents to the fabrics from a dilute solution such as is encountered in a rinse cycle. Attempts have been made to improve the efficiency of conditioning agent fabric deposition during the laundering process. For example, U.S. Pat. No. 3,442,692 overcomes the problem of delivery to the fabrics by adding the conditioning agent to the automatic dryer.
Another problem has been the attainment of satisfactory antistat properties on the dried fabrics. A static electric charge develops on fabrics during the tumbling of the fabrics in a clothes dryer. Such a charge is objectionable to the consumer because of difficulty it causes in sorting and folding of the dried fabrics. Conventional fabric softener delivered to the fabrics either in the rinse cycle or during the drying operation alleviates the problem of static electricity build up on the fabrics. However, it has been found that when the fabric softener is delivered in the rinse cycle, it hydrates with the water and partly migrates to the inner portions of the fabric. Since the build up of static electricity occurs across the surface portions of fabrics, the most beneficial use of the fabric softener for antistat benefits would be if it would substantially remain on the surface portions.
Treatment of fabrics after the drying operation has also been attempted. For example, U.S. Pat. No. 3,870,542 teaches the treatment of fibrous articles with a composition containing microcapsules. The microcapsules contain a solvent and a fabric conditioning agent. The treatment process comprises applying the microcapsules to the fabric and thereafter breaking the microcapsules to release the solvent solution onto the fibrous article. Such a process is not conducive to home laundering situations. Moreover, the presence of the solvent causes odor problems and is costly.
Copending, commonly assigned patent application Ser. No. 597,938 to Pracht, filed of even date and now abandoned, discloses the production of substantially solvent-free capsules having an inner core of a fabric antistat/softener material and an outer wall of a polycondensation product. A liquid fabric conditioning composition containing the capsules imparts satisfactory antistat control to fabrics rinsed with the composition in that the capsules are ruptured during the drying operation thereby releasing the fabric antistat/softener material onto the fabric surfaces. The capsules are produced by initially forming (1) a solution of melted fabric antistat/softener material having dissolved in it a first monomer capable of forming a polycondensation product along an interface with a second monomer and (2) an aqueous solution having dissolved in it the second monomer. The first solution is added to the aqueous solution under agitation to form capsules along the interface of the two solutions. However, it has been found that the raising of the temperature to melt the fabric antistat/softener makes it (as well as impurities such as water or isopropanol commonly found in commercial samples) more reactive and, hence, more likely to react with the dissolved monomer. This is, of course, undesirable in that it leads to side reactions and subsequent loss of monomer.
It accordingly is an object of this invention to provide a fabric conditioning composition intended for use in a home laundering operation wherein a fabric antistat/softener material can be effectively and efficiently applied to fibrous articles.
Another object of this invention is to provide a liquid fabric conditioning composition adapted to be added during the rinse cycle of the washing process which is capable of providing fabric antistat/softener properties to rinsed fibrous articles.
Still another object of this invention is to provide capsules containing a fabric antistat/softener material.
These and other objects will become apparent from the description which follows.
As used herein all percentages and ratios are by weight unless otherwise indicated.